Water at an average temperature of 110C and an average velocity of 2.5 m/s flows through a 7-m-long stainless-steel tube (k=14.2 W/m-C) in a boiler. The inner and outer diameters of the tube are D;= 1.0 cm and Do=1.4 cm, respectively. If the convection heat transfer coefficient at the outer surface of the tube where boiling is taking place is ho= 7200 W/m.C, determine the overall heat transfer coefficient U; of this boiler based on the inner surface area of the tube. Assume a fouling factor Rf = 0.0005 m.C/W on the inner surface of the tube. It is given that the properties of water at 110C are (Table A-9) = = 0.268 10-6 m/s, k = 0.682 W/m.C, and Pr = 1.58. The overall heat transfer coefficient of the boiler is | W/mC